1. Field of the Invention
This invention relates to a hydrostatic axial piston machine, in particular, to an axial piston motor with a rotating cylinder block which comprises a cylinder block body and a cylinder block neck, and a drive shaft. A plurality of piston bores are located in the cylinder block body. Longitudinally moveable pistons are located in the piston bores and are supported on a swashplate. A synchronization gearing is located between the cylinder block neck (which projects from the cylinder block body and extends in the direction of the swashplate) and the drive shaft. A braking device acts on the cylinder block.
2. Description of Related Art
In axial piston machines of the general type that employ a swashplate construction, the pistons, which can move longitudinally in the piston bores of the cylinder block, are supported on a swashplate. As a rule, the pistons are supported on the swashplate by a sliding shoe connected with the corresponding piston by a sliding shoe joint, such as a ball-and-socket joint. Torque is transmitted between the cylinder block and the drive shaft by a synchronization gearing, which makes possible both an axial mobility of the cylinder block and a limited angular adjustment capability of the cylinder block. As a result, the position of the cylinder block on a control plate can be adjusted. The cylinder block is supported on the drive shaft at the intersection between the plane of the midpoints of the sliding shoe joints and the axis of rotation of the drive shaft. In axial piston machines of the known art, this intersection lies axially outside the cylinder block, i.e., axially between the cylinder block and the swashplate. For this reason, on axial piston machines of the known art, the cylinder block body is elongated toward the swashplate by a projecting cylinder block neck. The synchronization gearing is located on or in the vicinity of the cylinder block neck. As a result, the transverse force that is generated by the resolution of forces on the sliding shoe joints can be transmitted and supported without causing undesirable tipping forces on the cylinder block. If, when viewed in the axial direction, the center of the overlap area between the synchronization gearing on the cylinder block neck essentially coincides with the intersection of the plane that is formed by the sliding shoe midpoints and the axis of rotation of the drive shaft or of the cylinder block, an undesirable tipping moment on the cylinder block that would lead to a tipping of the cylinder block away from the control surface can be prevented by the transverse forces that occur.
The design of an axial piston machine of the known art requires a low wall thickness of the cylinder block neck, which is drawn out from the cylinder block body in the axial direction and is provided with the hub profile of the synchronization gearing. As a result of the simultaneous transmission of the torque and the transverse force, high loads are exerted on the cylinder block neck and on the transition between the cylinder block neck and the cylinder block body, as a result of which a material with appropriately high strength must be used.
If a generic axial piston machine also has a braking device which acts on the cylinder block, preferably on the cylinder block body, when the braking device is actuated into the braking position, the braking torque is also applied to the synchronization gearing in the vicinity of the cylinder block neck. Additional loading and stressing of the synchronization gearing are caused by the braking torque, especially if hydrostatic forces and torques are transmitted simultaneously and the braking device is used as an operating brake to decelerate the rotating drive shaft.
The high stresses on the cylinder block neck are accompanied by the risk that the cylinder block neck may break away from the cylinder block body and become detached from the cylinder block body. The synchronization gearing between the cylinder block neck and the drive shaft can also fail. In the event of such failures that involve a failure of the synchronization gearing, the braking torque of the braking device can no longer be transmitted to the drive shaft on account of the lack of synchronization gearing between the drive shaft and the cylinder block neck, which results in a loss of the braking action.
Therefore, it is an object of the invention to provide an axial piston machine of the general type described above but in which the full functional capability of the braking device is preserved in the event of a failure of the synchronization gearing.